Find the equation of the secant line through the point where x has the given values

f(x)=squar root of x; x=25,x=36

I check the textbook, there just have the equation of tangent line...how can I find the equation of the secant line?

Feb 9th 2009, 11:39 PM

mollymcf2009

Quote:

Originally Posted by shannon1111

Find the equation of the secant line through the point where x has the given values

f(x)=squar root of x; x=25,x=36

I check the textbook, there just have the equation of tangent line...how can I find the equation of the secant line?

Use the difference quotient to find the slope of the secant line. The slope of the secant line is your average rate of change of your function.

You find the slope of the tangent line by taking the derivative of your function. You can also find it by using the difference quotient from the secant line by taking it at the limit of the point of tangency. The slope of the tangent line is the instantaneous rate of change at that exact point on your curve.

Feb 10th 2009, 07:47 AM

HallsofIvy

Another way of saying the same thing mollymcf2009 did: A secant line to a curve is just a line through two points on the curve. It's actually easier to find than the tangent line. If x= 25 and , what is y? If x= 36, what is y? Find the equation of the line through those two points.